The therapies involved are mainly those of the ablation kind with the aid of an ablation catheter. For the therapy of atrial fibrillation in the heart, for example, the pulmonary veins of the atrium are electrically isolated by annular ablations around the pulmonary veins. The procedure for carrying out annular ablation is very complex.
Arrythmias in ventricular movement (ventricular fibrillation) can result from scar tissue in the myocardium. This scar tissue forms as a result of an infarction, for example. An accurately targeted ablation on the scar tissue may suppress the ventricular fibrillation. Here, too, ablation is very difficult to carry out because of the requirement for accurate targeting.
Hitherto, two kinds of image data have been used for visually supporting an invasive therapy of the heart with the aid of an ablation catheter:
Firstly, three-dimensional image data acquired prior to the actual operation are used. In these three-dimensional image data the areas requiring ablation can be recognized. The problem lies in aligning three-dimensional image data with the position of the ablation catheter.
Orientation systems provided on the ablation catheter, such as the CARTO system from Biosense Webster, for example, are usually used, optionally with the assistance of a further catheter. Electro-anatomical maps can be produced with the aid of these systems, the maps essentially being a representation in image form of electrophysiological cardiac signals as a function of the position of a signal recorder.
The maps can also be used effectively during ablation.
In order to be able to use the three-dimensional image data that have been acquired prior to therapy at the same time as the maps, registration of three-dimensional image data with electroanatomical maps can be carried out. “Registration” is understood here to mean that electroanatomical 3D mapping data can be aligned with the 3D image data in the correct position and dimensions, that is, that the systems of co-ordinates are combined with each other. This is disclosed, for example, in DE 103 405 44 A1.
Aligning 3D mapping data with one another in the correct position and dimension is very time-consuming, however.
A registration is also carried out in a method known from DE 102 10 645 A1 for detecting and imaging a medical catheter inserted in an area of a patient to be examined. There is a position-detecting means on the medical catheter, the means being part of a position-detection system, and the system of co-ordinates of the position-detection system is registered with the system of co-ordinates of a 3D construction image produced with the aid of an X-ray C-arm. This allows the tip of the catheter to be displayed in the 3D reconstruction image on a monitor.
EP 1 504 713 A1 discloses a navigation system for cardiac therapies, in which a medical catheter is equipped with electromagnetic coils as sensors for a navigation system.